pCAL expression vectors

I am planning to use vector pCAL-n to express proteins in E. coli
(Stratagene). I would welcome any comment or advice from people
having tried one of the pCAL vectors (pCAL-n, pCAL-c, pCAL-kc, pCAL-n-EK)
Thank you very much in advance.
Daniel MARC
INRA - Centre de TOURS
37380 Nouzilly, France
marc at tours.inra.fr